1. Field of the Invention
The present invention relates to a technique of manufacturing semiconductor devices including a cleaning step, and, more particularly, to a technique of manufacturing semiconductor devices including a cleaning step for removing a foreign matter or the like which remains on the surface of a semiconductor wafer.
2. Description of the Prior Art
The technique of fabricating semiconductor devices (such as LSI and VLSI) has rapidly been advanced for device miniaturization. Cleaning of a semiconductor wafer in the manufacturing steps for a semiconductor device is one of important processes to improve the production yield of semiconductor devices. In this respect, cleaning is performed as a preprocess or a postprocess of each manufacturing step, such as deposition or etching.
Conventionally, cleaning of a semiconductor wafer (hereinafter called xe2x80x9cwaferxe2x80x9d) is carried out by washing a foreign matter off the wafer surface by dipping the wafer in pure water or a solution having various kinds of acids or an alkaline solution diluted in pure water or spraying the pure water or the solution to the wafer. Also available is a scheme of dipping a wafer in such a solution and, at the same time mechanically cleaning the wafer surface by a brush. Those cleaning schemes are called wet cleaning as they use a solution.
However, wet cleaning requires steps following the cleaning step, such as rinsing and drying, thus increasing the number of manufacturing steps.
Dry cleaning is a solution to the problem of wet cleaning.
One type of dry cleaning is disclosed in, for example, Japanese Patent Laid-Open No. 131981/1996 (hereinafter referred to as xe2x80x9cprior art document 1xe2x80x9d). The prior art document 1 describes that an object to be cleaned (specimen) is a 6-inch silicon wafer which is, for example, single-crystalline silicon sliced, lapped and polished, and a matter stuck on the specimen to be cleaned due to static-electricity originated charging is cleaned by a nominal temperature dry method using activated air. That is, in the cleaning step, the active air includes air ions and water cluster, forms a high-humidity atmosphere and contacts the specimen to be cleaned in a cleaning chamber while flowing. The air ions neutralize charges of the specimen to be cleaned, and the water cluster frees the stuck matter from the surface of the specimen to be cleaned. The flowing active air separates and removes the stuck matter from the specimen to be cleaned. The prior art document 1 specifically discloses preprocess cleaning at the time of manufacturing an LSI after Si wafers are purchased from a wafer maker.
Another dry cleaning is disclosed in Japanese Patent Laid-Open No. 85887/1996 (hereinafter referred to as xe2x80x9cprior art document 2xe2x80x9d). The prior art document 2 describes that after a specimen which has a single-layer film or a multi-layer film containing W as a to-be-etching material is subjected to an etching process, the specimen is transferred to a postprocessing apparatus (a processing apparatus in a next step) by a vacuum transfer apparatus. Then, a photoresist and a stuck matter are simultaneously removed (plasma ashing) in that processing apparatus (in vacuum) without exposing the specimen to the air.
Different dry cleaning is disclosed in Japanese Patent Laid-Open No. 17776/1997 (hereinafter referred to as xe2x80x9cprior art document 3xe2x80x9d). According to the prior art document 3, in forming a film whose deposition thickness is apt to be affected by an adsorbed organic matter on a semiconductor substrate, O3 cleaning is performed, before the deposition of a base film, at room temperature or a high temperature in the same semiconductor device manufacturing apparatus to remove the adsorbed organic matter, thereby stabilizing deposition which is likely to be affected by the surface state of the semiconductor substrate. That is, according to the subject matter described in the prior art document 3, by directly using the semiconductor device manufacturing apparatus that has formed an underlying interconnection pattern on a semiconductor substrate, an O3 gas is fed to clean the semiconductor substrate and is reacted with a residual organic matter on the surface of the semiconductor substrate to remove the residual organic matter as a volatile matter, such as CO or CO2, and a film which is unstable to an organic matter is deposited as an interlayer insulating film, after removal of the residual organic matter, via a base film without being affected by the residual organic matter.
Recently, the mainstream has changed from small-commodity mass-production typified by production of DRAMs to large-commodity mass-production symbolized for on chips (so-called system LSIs). In the case of large-commodity mass-production, attention has been paid to shorten the TAT (Turn Around Time) in order to improve the production efficiency.
Therefore, dry cleaning is demanded as cleaning which is performed as a preprocess or postprocess in the process of manufacturing a semiconductor device in order to improve the efficiency of manufacturing a semiconductor device.
Further, an improvement on the performance of dry cleaning is demanded to improve the production yield of semiconductor devices.
Accordingly, it is an object of the invention to efficiently process a substrate and perform cleaning to remove a foreign matter after the process.
It is another object of the invention to provide a novel method for manufacturing a semiconductor device suitable for miniaturization.